First of all, gaining muscle is definitely not that easy. I lift extremely heavy, follow a strict diet that is aimed towards gaining muscle and it still takes me a long time to put muscle on my frame. So lifting weight that weighs more than you're water bottle is definitely okay! I do understand that not everyone wants or likes the same look and therefore different training programs are designed for different people focusing on ones specific goals. But in order for one to make progress you have to stimulate the muscles and challenge the body with something that it hasn't already adapted to.
Secondly, women have about 15 to 20 times less testosterone than men therefore men have the ability to gain a lot more muscle than women. Many times women will see female bodybuilders on the covers of magazines and think they will look like them if they lift weights. This is not the case. A woman who is natural and starts a strength training program will not wake up looking like a female bodybuilder but instead will have improved muscular development and a leaner athletic appearance following they have a clean diet as well.
So ladies, instead of doing a set of 10 with a weight that you could do 20 or 30 reps with try going up in weight that you fail out at 10-15 with. When that weight becomes easy, add more resistance. If you follow the same training regime without ever changing up the sets, reps, weight or intensity you will plateau and fail to see results. So get in there and don't be afraid of the weight room! :)